Thermal barrier coating material, gas turbine parts and gas turbine

a technology of thermal barrier coating and gas turbine, which is applied in the direction of surface reaction electrolytic coating, liquid fuel engine components, non-positive displacement fluid engines, etc., can solve the problems of insufficient crystalline stability, insufficient durability, and insufficient crystalline stability, so as to achieve high thermal cycle durability, reduce the effect of thermal cycle stress

Inactive Publication Date: 2005-07-12
MITSUBISHI HEAVY IND LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0006]The present invention has been made in consideration of the problems described above, and an object thereof is to provide a thermal barrier coating material that can prevent spall-off from occurring during operation at high temperatures and has a high heat insulating effect.
[0008]Spall-off of the ceramic layer made of YSZ occurs because of insufficient crystalline stability of the YSZ at high temperatures and insufficient durability against high thermal stresses. The present inventors have researched the constitution of a thermal barrier coating material that can improve the crystalline stability of the YSZ at high temperatures and the thermal cycle durability of the ceramic layer. The present invention has been completed upon finding that the durability of the thermal barrier coating material can be improved by forming a ceramic layer from ZrO2 stabilized with Er2O3. Hereinafter, the ZrO2 stabilized with Er2O3 will be referred to as “ErSZ”.
[0009]The thermal barrier coating material of the present invention comprises a ceramic layer comprising ZrO2 and Er2O3. The Er2O3 functions as a stabilizing agent. The thermal barrier coating material of such a composition has higher crystalline stability at higher temperatures than ceramic layers made of the YSZ of the prior art, thus making it possible to achieve excellent thermal cycle durability. The thermal barrier coating material of the present invention is preferably formed on a high temperature heat-resistant alloy base in order to improve the heat resistance of the base.
[0011]The ceramic layer comprising ZrO2 stabilized with Er2O3 employed in the present invention, in contrast, has high crystalline stability that makes phase transformation less likely to occur than in a ceramic layer made of YSZ. Therefore, occurrence of stress due to phase transformation can also be restricted. Thus the thermal barrier coating material of the present invention achieves high thermal cycle durability.

Problems solved by technology

Spall-off of the ceramic layer made of YSZ occurs because of insufficient crystalline stability of the YSZ at high temperatures and insufficient durability against high thermal stresses.

Method used

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  • Thermal barrier coating material, gas turbine parts and gas turbine
  • Thermal barrier coating material, gas turbine parts and gas turbine
  • Thermal barrier coating material, gas turbine parts and gas turbine

Examples

Experimental program
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example 1

[0043]In this example, samples having ErSZ layers formed from ZrO2 with varying Er2O3 content were fabricated and tested to measure the thermal cycle life, in order to determine the change in the thermal cycle life with the changing quantity of Er2O3 content. Ni-based heat-resistant alloy with the composition of Ni—16Cr—8.5Co—1.7Mo—2.6W—1.7T—0.9Nb—3.4Al—3.4Ti was used for the base of the samples. After sand-blasting the base surface with Al2O3 particles, the surface was coated with a CoNiCrAlY alloy that has a composition of Co—32Ni—21Cr—8Al—0.5Y by a low-pressure plasma thermal spray process so as to form a bonding coat layer. Then a ceramic layer (ErSZ layer) was formed by an atmospheric plasma thermal spray process on the bonding coat layer made of the CoNiCrAlY alloy, thereby forming the thermal barrier coating material. The Er2O3 content in the ceramic layers of different samples (samples Nos. 1 to 12) are shown in Table 1.

[0044]The bonding coat layer (CoNiCrAlY) was formed to ...

example 2

[0052]Next, in order to study the change in durability with different void ratios in the ceramic layer made of ErSZ, samples were made by forming thermal barrier coating material films, having the ceramic layers of different void ratios shown in Table 2, on bases. Void ratios in the ceramic layers of these samples were set to predetermined values by controlling the thermal spray flow and distance. Samples Nos. 15 to 23 were made same manner as in Example 1, except for controlling the void ratio and setting the Er2O3 content to 18% by weight.

[0053]As shown in Table 2, samples Nos. 18 to 20 having void ratios of the ceramic layer within a range from 8% to 15% proved to have higher thermal cycle durability than the thermal barrier coating material film having the ceramic layer made of YSZ of the prior art shown in Table 1.

[0054]

TABLE 2Er2O3 contentVoid ratio afterSample No.(Wt %)thermal sprayingThermal cycle life1518 2%51618 4%151718 6%1501818 8%894191812%>3000201815%1576211820%1652218...

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Abstract

A thermal barrier coating material can prevent spall-off from occurring during operation at high temperatures and has a high heat insulating effect. A turbine parts and a gas turbine that are protected with the thermal barrier coating material are also provided. The thermal barrier coating material of the present invention comprises a ceramic layer 23, which is formed on a high temperature heat-resistant alloy base 21 to protect the base 21 from high temperatures, the ceramic layer 23 being applied via a bonding coat layer 22 provided as a metal bonding layer and is made of ZrO2 with Er2O3 added thereto as a stabilizing agent. The turbine parts and the gas turbine of the present invention are coated with the thermal barrier coating material on the surfaces thereof.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a thermal barrier coating material, a gas turbine parts, and a gas turbine that have high durability and, more particularly, relates to the constitution of a ceramic layer used as a top coat for the thermal barrier coating material.[0003]2. Description of the Related Art[0004]It has been attempted in recent years to improve the thermal efficiency of thermal power generation as part of efforts to reduce energy consumption. To improve the thermal efficiency of a gas turbine used in thermal power generation, it is effective to raise the temperature at the gas inlet, which may often be set to about 1500° C. Operating a power generator at such a high temperature requires building stationary vanes and rotor blades that constitute the gas turbine and / or the wall of a combustor with materials that can endure the high temperature. The turbine blades are made of heat-resistant metal but cannot end...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): C23C30/00C23C4/10C23C28/00F01D5/28F02C7/00
CPCC23C4/105C23C28/3215C23C28/3455C23C30/00Y10T428/12618Y02T50/67Y10T428/1259Y10T428/12611C23C4/11Y10T428/249953Y10T428/249956Y10T428/249967Y02T50/60
Inventor TORIGOE, TAIJIAOKI, SUNAOMORI, KAZUTAKAOKADA, IKUOTAKAHASHI, KOUJI
Owner MITSUBISHI HEAVY IND LTD
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